Aerial lifts provide a mobile and aerial work platform which may be used for a variety of purposes. Such aerial lifts are usually mounted on a truck or other vehicle and have a lower boom, an upper boom and a personnel carrier bucket attached to the upper boom. The operator, upon climbing into the bucket, is able to change his position relative to the ground by controlling the movements of the lower boom, the upper boom or both. The lower boom pivots about one end in a generally vertical plane, the upper boom pivots about the upper end of the lower boom in roughly the same vertical plane, and both booms together rotate or swing about a vertical axis. The controls for each of these boom movements are often combined into a single control handle, which handle is located to one side of the bucket. Prior art control handles allow for one-handed control and can be moved in various directions to affect boom movement.
Some types of non-telescoping aerial lifts have an overcenter capability wherein the upper boom is able to unfold from the stowage position and rotate past a center position which is where the longitudinal axis of the upper boom is vertical. Overcenter positions of the upper boom are used for obtaining maximum working reaches of a particular aerial lift. When the operator unfolds or raises the upper boom and thus the bucket from the stowage position, he is in the non-overcenter zone of operation. As the upper boom continues to unfold, it will reach a center position and will then enter into the overcenter zone of operation.
When controlling the movements of the booms, the operator will usually face outwardly (that is the direction away from the above-mentioned imaginary vertical line extending through the lower boom upper end portion) and place one hand on the control handle. It is preferable for the bucket to move generally in the same direction as the control handle is moved. That is, the direction of elevation of the booms and the direction of their rotation about the vertical axis of the pedestal structure will generally correspond with the directions of control handle movements. Prior art control handles typically provide for correspondence between handle motion and bucket motion (boom elevations and rotation) in the non-overcenter zone. However, this correspondence between the handle and bucket motions is not carried over into all operational zones by any prior art control handles. As the bucket goes into some operational zones, for example, the overcenter zone of operation from the non-overcenter zone of operation, the operator turns around inside of the bucket 180.degree. to again face outwardly and thereby places his other hand on the control handle so as to control the movements of the booms. While in the overcenter zone of operation, the necessary control handle movements, for upper boom and swing control, relative to the desired direction of bucket movement reverse from the non-overcenter control handle movements. The bucket operator may easily become confused when deciding how to move the bucket in the overcenter zone of operation, as a result of the switching of hands and changes in the requisite control handle movements.
In addition, the control handles of the prior art have been deficient in providing the operator with comfort and convenience in reaching and manipulating the control handle.
The objective of the present invention is to provide a control handle arrangement that provides correspondence between handle motion and bucket motion for all zones of operation, while at the same time providing the operator with comfort and convenience in reaching and manipulating the control handle.